Hitchhikers: Tupolev I-4, Polikarpov I-16
Motherships: Tupolev TB-1, TB-3
Soviet Union, 1930s
By the 1930s, the Soviets were coming around to the idea of using parasites for combat. Zveno (“Link”) was an experimental program that combined bombers with air-launched fighters to increase range and payloads.
The I-4 fighter was the first little airplane to emerge from A.N. Tupolev’s aeronautical design company, known for its fleet of plus-size types. The I-4 didn’t get attention for its size, though; the aircraft was the Soviet Union’s first all-metal fighter.
Two slightly modified I-4s, outfitted with three connector clips and a release mechanism, were rolled up wooden ramps to the wings of a Tupolev TB-1 bomber. On Zveno-1’s maiden flight, the two I-4s launched, but not, as planned, simultaneously. The error proved the TB-1 would remain stable in the air, even with a weight imbalance. The project was considered a success, and though the I-4 remained in service until 1933, it did not fly as a parasite in combat.
That duty was given to the most successful experiment, the Zveno-SPB (Russian acronym for “composite dive bomber”). After it saw combat, the small, beefy Polikarpov I-16 earned Soviet aircraft designers a reputation for ingenuity, though its nickname was less than dignified: “donkey”—a play on the Russian pronunciation of “I-16.”
The barrel-chested donkey was the Soviets’ first cantilever-wing monoplane fighter, and the first to have retractable landing gear. Its design showed creativity in a time when much of Soviet technology involved copycat production.
The I-16 could carry two bombs while attached underwing to a Tupolev TB-3, a more powerful bomber than its TB-1 predecessor. The TB-3’s four engines and each I-16 single engine worked together, and the I-16s drew fuel from the TB-3 while connected.
The Zveno-SPB was used in combat between 1936 and 1941 and flew several successful missions against German forces in Romania’s Black Sea ports. In 29 missions, only three I-16s were lost.